#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
typedef long long ll;
const ll mod = 998244353;
int main(){
  ll N; cin >> N;
  ll MAX = 1e7 + 10;
  vector<ll> prime(MAX, -1);
  prime[0] = prime[1] = 1;
  for(int i = 2; i < MAX; i++){
    if(prime[i] == -1){
      prime[i] = i;
      for(int j = 2; i * j < MAX; j++){
        if(prime[i * j] == -1) prime[i * j] = i; 
      }
    }
  }
  ll ans = 0;
  for(ll i = 1; i <= N; i++){
    if(i == 1) ans++;
    else{
      set<ll> st;
      ll nN = i;
      bool zero = false;
      ll cnt = 0;
      while(nN > 1){
        if(nN % (prime[nN] * prime[nN]) == 0){
          zero = true;
          break;
        }
        nN /= prime[nN];
        cnt++;
      }
      if(!zero) ans += ((cnt & 1) ? -1 : 1);
    }
  }
  cout << ans << endl;
}